Gross motor change after inpatient rehabilitation for children with acquired brain injury: A 10-year retrospective review.

AIM: To estimate gross motor change in inpatient school-aged children with subacute acquired brain injury (ABI), identify factors associated with gross motor change, and describe inpatient physiotherapy focus. METHOD: This retrospective chart review involved inpatient children (5-18 years) with subacute ABI who had either two Gross Motor Function Measure (GMFM-88) assessments or one GMFM-88 with another pre/post gross motor outcome measure. Outcome change scores and Goal Attainment Scaling (GAS) T scores were calculated. Regression analyses examined factors predicting gross motor change. GAS goal areas were analysed to determine physiotherapy focus. RESULTS: Of the 546 charts screened, 266 (118 female) met study criteria. The GMFM-88 was generally administered first, followed by other measures. GMFM-88 (n = 202), Community Balance and Mobility Scale (n = 89), and Six-Minute Walk Test (6MWT) (n = 98) mean change scores were 18.03% (SD 19.34), 17.85% (SD 10.77), and 142.3 m (SD 101.8) respectively. The mean GAS T score was 55.06 (SD 11.50). Lower baseline scores and increased time between assessments were most predictive of greater GMFM-88 change (r ≥ 0.40). Twenty-five percent of GAS goals were ambulation-based. INTERPRETATION: Appropriate outcome measure selection is integral to detecting gross motor change in pediatric inpatient ABI rehabilitation. Mean change score estimates can be used to compare standard inpatient rehabilitation with new treatment approaches.

Generating Items for a Novel Bedside Dysphagia Screening Tool Post Acute Pediatric Stroke.

Bedside dysphagia assessment protocols are not well developed in acute pediatric stroke unlike adults. The objective of this study was to identify items deemed relevant and feasible by expert consensus to inform the development of a bedside dysphagia screening tool for acute pediatric stroke. A two-phase study was conducted: (1) literature review and expert consultation generated a comprehensive list of dysphagia assessment items; (2) items were formatted in an online survey asking respondents opinion of relevance to acute pediatric stroke and feasibility for bedside administration by a trained health professional. The Dillman Tailored Design approach optimized response rate. Respondents were identified using the snowball method. Speech-language pathologists with > 2 years in pediatric dysphagia were invited to complete the survey. Demographic and practice variables were compared using univariate statistics. Item relevance and feasibility were made using binary or ordinal responses, combined to derive item-content validity indices (I-CVI) to guide item reduction. Items with I-CVI > 0.78 (excellent content validity) were moved forward to tool development. Of the 71 invited respondents, 57(80.3%) responded, of which 34(59.6%) were from North America. Sixty-one items were generated of which 4(6.6%) items were rated 'to keep'. These were face symmetry (I-CVI:0.89), salivary control (I-CVI:0.95), alertness (I-CVI:0.89) and choking (I-CVI:0.84). Of all respondents, 31(54.4%) endorsed swallowing trials, of which 25(80.6%) endorsed thin liquid by teaspoon (n = 17, 68%) or open cup (n = 20, 80%). We identified candidate items for bedside dysphagia screening with excellent content validity for acute pediatric stroke patients. Next steps include assessment of the psychometric value of each item in identifying dysphagia in children in the acute stage of recovery from stroke.

Integrating Transcranial Direct Current Stimulation into an Existing Inpatient Physiotherapy Program to Enhance Motor Learning in an Adolescent with Traumatic Brain Injury: A Case Report.

PURPOSE: Describe how transcranial direct current stimulation (tDCS) was incorporated into an inpatient physiotherapy program for an adolescent with severe traumatic brain injury (TBI), detail the motor learning focus of the physiotherapy sessions, and summarize gross motor progress. METHOD: This case report describes an adolescent who received 20 minutes of anodal tDCS immediately prior to 16 physiotherapy sessions over four weeks. Potential side effects were tracked pre/post tDCS. Gross motor outcomes were measured pre-intervention, post-intervention, and three months post-intervention. Physiotherapy session content was analyzed using therapist documentation and the Motor Learning Strategies Rating Instrument. RESULTS: The youth tolerated tDCS well. The primary side effect was itchiness under the electrodes during tDCS sessions. His mobility progressed from wheelchair use pre- 'tDCS + physiotherapy' to ambulation with a walker post-intervention. His Gross Motor Function Measure score increased 33.1% points pre/post intervention. Session tasks often had several foci (e.g., skill acquisition, strength, and balance) with task focus changing as the youth progressed. Various motor learning strategies were layered within tasks to support performance and learning. CONCLUSIONS: tDCS was successfully integrated into an existing inpatient physiotherapy program for an adolescent with TBI. This protocol provides a structure for implementing, monitoring, and measuring tDCS + physiotherapy in pediatric rehabilitation.

Effects of Pediatric Traumatic Brain Injury on Verbal IQ: A Systematic Review and Meta-Analysis.

OBJECTIVES: To examine the effects of pediatric traumatic brain injury (TBI) on verbal IQ by severity and over time. METHODS: A systematic review and subsequent meta-analysis of verbal IQ by TBI severity were conducted using a random effects model. Subgroup analysis included two epochs of time (e.g., <12 months postinjury and ≥12 months postinjury). RESULTS: Nineteen articles met inclusion criteria after an extensive literature search in MEDLINE, PsycInfo, Embase, and CINAHL. Meta-analysis revealed negative effects of injury across severities for verbal IQ and at both time epochs except for mild TBI < 12 months postinjury. Statistical heterogeneity (i.e., between-study variability) stemmed from studies with inconsistent classification of mild TBI, small sample sizes, and in studies of mixed TBI severities, although not significant. Risk of bias on estimated effects was generally low (k = 15) except for studies with confounding bias (e.g., lack of group matching by socio-demographics; k = 2) and measurement bias (e.g., outdated measure at time of original study, translated measure; k = 2). CONCLUSIONS: Children with TBI demonstrate long-term impairment in verbal IQ, regardless of severity. Future studies are encouraged to include scores from subtests within verbal IQ (e.g., vocabulary, similarities, comprehension) in addition to functional language measures (e.g., narrative discourse, reading comprehension, verbal reasoning) to elucidate higher-level language difficulties experienced in this population.

Parent Interventions Improve Behavior After Pediatric Traumatic Brain Injury: A Systematic Review and Meta-analysis.

OBJECTIVE: To examine child behavior change scores from randomized controlled trials (RCTs) of parent interventions for pediatric traumatic brain injury (TBI). METHODS: MEDLINE, EMBASE, PsycINFO, and CINAHL were searched to identify studies that examined parent interventions for pediatric TBI. Inclusion criteria included (i) a parent intervention for children with TBI; (ii) an RCT study design; (iii) statistical data for child behavior outcome(s); and (iv) studies that were published in English. RESULTS: Seven studies met inclusion criteria. All interventions reported improved child behavior after pediatric TBI; however, child and parent factors contributed to behavior change scores in some interventions. Factors found to contribute to the level of benefit included age of child, baseline behavior levels, sociodemographics (eg, parent income, parent education), and parent mental health. CONCLUSION: Improved child behavior outcomes resulting from parent interventions for pediatric TBI are well supported by the evidence in the peer-reviewed literature. Clinicians are encouraged to consider child and parent factors as they relate to child behavior outcomes.

Decreased automaticity contributes to dual task decrements in older compared to younger adults.

PURPOSE: To contrast older and younger adults' prefrontal cortex (PFC) neural activity (through changes in oxygenated hemoglobin) during single and dual tasks, and to compare decrements in task performance. METHODS: Changes in oxygenated hemoglobin of dorsolateral PFC were monitored using functional near-infrared spectroscopy during single tasks of spelling backwards (cognitive task) and 30 m preferred paced walk; and a dual task combining both. Gait velocity was measured by a pressure sensitive mat. RESULTS: Twenty sex-matched younger (27.6 ± 3.5 years) and 17 older adults (71.2 ± 4.9 years) were recruited. The left PFC oxygenated hemoglobin decreased from start (1st quintile) to the end (5th quintile) of the walking task in younger adults ( - 0.03 ± 0.03 to - 0.72 ± 0.20 µM; p < .05) unlike the non-significant change in older adults (0.03 ± 0.06 to - 0.41 ± 0.32 µM, p > .05). Overall, oxygenation increased bilaterally during dual versus single walk task in older adults (Left PFC: 0.22 ± 0.16 vs. - 0.23 ± 0.21 µM, respectively; Right PFC: 0.17 ± 0.18 vs. - 0.33 ± 0.22 µM, respectively), but only in right PFC in younger adults ( - 0.02 ± 0.15 vs. - 0.47 ± 0.13 µM). Older adults exhibited lower velocity during the dual task compared to younger adults (1.03 ± 0.16 vs. 1.20 ± 0.17 m/s, respectively). Older age was associated with dual task cost on velocity during walking after adjusting for confounding variables. CONCLUSIONS: Age-related cognitive decline in older adults may increase neural activity for cognitive tasks and diminish walking automaticity that may lead to decrements during dual tasking; the greater PFC increases in the oxygenated hemoglobin and lower velocity may be due to increased cognitive load and limited attentional resources.

The effect of transcranial direct current stimulation on cognitive performance in youth with persistent cognitive symptoms following concussion: a controlled pilot study.

OBJECTIVE: Explore the feasibility, tolerability, and early efficacy of transcranial direct current stimulation (tDCS) as a therapeutic intervention for youth with cognitive persistent post-concussion symptoms (PPCS). HYPOTHESIS: tDCS improves performance on a dual task working memory (WM) paradigm in youth with cognitive PPCS. PARTICIPANTS: Twelve youth experiencing cognitive PPCS. DESIGN: A quasi-randomized pilot trial was used to explore the tolerability of, and performance differences on, a dual N-Back WM task paired with active or sham tDCS over 3 sessions. MEASURES: Accuracy and reaction time on WM task and self-report of tDCS tolerability. RESULTS: Trends toward increases in accuracy from Day 1 to 3 seen in both groups. Active tDCS group performed better than sham on Day 2 in N-Back level N2 (p = .019), and marginally better than the sham group on Day 3 in level N3 (p = .26). Participants reported tDCS as tolerable; compared to the active tDCS group, the sham group reported more "considerable" (p = .078) and "strong" symptoms (p = .097). CONCLUSION: tDCS is a promising tool for enhancing WM performance and is a feasible and tolerable adjunct to behavioral interventions in youth with cognitive PPCS. A clinical trial to demonstrate efficacy is warranted.

Swallowing, Oral Motor, Motor Speech, and Language Impairments Following Acute Pediatric Ischemic Stroke.

BACKGROUND AND PURPOSE: Following adult stroke, dysphagia, dysarthria, and aphasia are common sequelae. Little is known about these impairments in pediatric stroke. We assessed frequencies, co-occurrence and associations of dysphagia, oral motor, motor speech, language impairment, and caregiver burden in pediatric stroke. METHODS: Consecutive acute patients from term birth-18 years, hospitalized for arterial ischemic stroke (AIS), and cerebral sinovenous thrombosis, from January 2013 to November 2018 were included. Two raters reviewed patient charts to detect documentation of in-hospital dysphagia, oral motor dysfunction, motor speech and language impairment, and caregiver burden, using a priori operational definitions for notation and assessment findings. Other variables abstracted included demographics, preexisting conditions, stroke characteristics, and discharge disposition. Impairment frequencies were obtained by univariate and bivariate analysis and associations by simple logistic regression. RESULTS: A total of 173 patients were stratified into neonates (N=67, mean age 2.9 days, 54 AIS, 15 cerebral sinovenous thrombosis) and children (N=106, mean age 6.5 years, 73 AIS, 35 cerebral sinovenous thrombosis). Derived frequencies of impairments included dysphagia (39% neonates, 41% children); oral motor (6% neonates, 41% children); motor speech (37% children); and language (31% children). Common overlapping impairments included oral motor and motor speech (24%) and dysphagia and motor speech (23%) in children. Associations were found only in children between stroke type (AIS over cerebral sinovenous thrombosis) and AIS severity (more severe deficit at presentation) for all impairments except feeding impairment alone. Caregiver burden was present in 58% patients. CONCLUSIONS: For the first time, we systematically report the frequencies and associations of dysphagia, oral motor, motor speech, and language impairment during acute presentation of pediatric stroke, ranging from 30% to 40% for each impairment. Further research is needed to determine long-term effects of these impairments and to design standardized age-specific assessment protocols for early recognition following stroke.

Human larynx motor cortices coordinate respiration for vocal-motor control.

Vocal flexibility is a hallmark of the human species, most particularly the capacity to speak and sing. This ability is supported in part by the evolution of a direct neural pathway linking the motor cortex to the brainstem nucleus that controls the larynx the primary sound source for communication. Early brain imaging studies demonstrated that larynx motor cortex at the dorsal end of the orofacial division of motor cortex (dLMC) integrated laryngeal and respiratory control, thereby coordinating two major muscular systems that are necessary for vocalization. Neurosurgical studies have since demonstrated the existence of a second larynx motor area at the ventral extent of the orofacial motor division (vLMC) of motor cortex. The vLMC has been presumed to be less relevant to speech motor control, but its functional role remains unknown. We employed a novel ultra-high field (7T) magnetic resonance imaging paradigm that combined singing and whistling simple melodies to localise the larynx motor cortices and test their involvement in respiratory motor control. Surprisingly, whistling activated both 'larynx areas' more strongly than singing despite the reduced involvement of the larynx during whistling. We provide further evidence for the existence of two larynx motor areas in the human brain, and the first evidence that laryngeal-respiratory integration is a shared property of both larynx motor areas. We outline explicit predictions about the descending motor pathways that give these cortical areas access to both the laryngeal and respiratory systems and discuss the implications for the evolution of speech.

The Effect of Childhood Traumatic Brain Injury on Verbal Fluency Performance: A Systematic Review and Meta-Analysis.

Verbal fluency is a neuropsychological measure commonly used to examine cognitive-linguistic performance as reported in pediatric TBI literature. We synthesized the scholarly literature of verbal fluency performance in pediatric TBI and estimated the effects of TBI according to: (i) type of verbal fluency task (phonemic or semantic), (ii) severity of TBI, and (iii) time post-injury. Meta-analysis revealed that childhood TBI negatively impacted phonemic fluency and semantic fluency and that effect sizes were larger for children with more severe TBI. The negative effect of TBI was evident across time post injury within each level of severity. Verbal fluency tasks are efficient indicators of potential underlying impairments in lexical knowledge and executive functioning in children with TBI regardless of severity of injury or time post injury. Future research employing verbal fluency tasks are encouraged to explore if age at injury differentiates semantic versus phonemic fluency outcomes across severity levels.

Paradoxical facilitation alongside interhemispheric inhibition.

Neurophysiological experiments using transcranial magnetic stimulation (TMS) have sought to probe the function of the motor division of the corpus callosum. Primary motor cortex sends projections via the corpus callosum with a net inhibitory influence on the homologous region of the opposite hemisphere. Interhemispheric inhibition (IHI) experiments probe this inhibitory pathway. A test stimulus (TS) delivered to the motor cortex in one hemisphere elicits motor evoked potentials (MEPs) in a target muscle, while a conditioning stimulus (CS) applied to the homologous region of the opposite hemisphere modulates the effect of the TS. We predicted that large CS MEPs would be associated with increased IHI since they should be a reliable index of how effectively contralateral motor cortex was stimulated and therefore of the magnitude of interhemispheric inhibition. However, we observed a strong tendency for larger CS MEPs to be associated with reduced interhemispheric inhibition which in the extreme lead to a net effect of facilitation. This surprising effect was large, systematic, and observed in nearly all participants. We outline several hypotheses for mechanisms which may underlie this phenomenon to guide future research.

Sports Related Concussion Impacts Speech Rate and Muscle Physiology.

OBJECTIVE: Establish objective and subjective speech rate and muscle function differences between athletes with and without sports related concussion (SRC) histories and provide potential motor speech evaluation in SRC. METHODS: Over 1,110 speech samples were obtained from 30, 19-22 year-old athletes who had sustained an SRC within the past 2 years and 30 pair-wise matched control athletes with no history of SRC. Speech rate was measured via average time per syllable, average unvoiced time per syllable, and expert perceptual judgment. Speech muscle function was measured via surface electromyography over the obicularis oris, masseter, and segmental triangle. Group differences were assessed using MANOVA, bootstrapping and predictive ROC analyses. RESULTS: Athletes with SRC had slower speech rates during DDK tasks than controls as evidenced by longer average time per syllable longer average unvoiced time per syllable and expert judgment of slowed rate. Rate measures were predictive of concussion history. Further, athletes with SRC required more speech muscle activation than controls to complete DDK tasks. CONCLUSION: Clear evidence of slowed speech and increased muscle activation during the completion of DDK tasks in athletes with SRC histories relative to controls. Future work should examine speech rate in acute concussion.

Pediatric concussion working memory outcomes: a scoping review.

Objective: Characterize the working memory (WM) profile of children and youth who have experienced concussion by systematically synthesizing existing literature on the neuropsychological outcomes of these injuries.Methods: Implemented a peer-reviewed search strategy combining key concepts of concussion/mild traumatic brain injury (mTBI), WM, and pediatrics across MedLine, Embase, PsycINFO, and CINAHL. Included studies written in English with extractable results on a WM outcome measure in individuals aged 21 and under who experienced concussion. Applied narrative synthesis to identify trends in the literature. Assessed risk of bias and quality using the NHLBI's Quality Assessment of Observational Cohort and Cross-Sectional Studies.Results: 40 articles met inclusion criteria. 34/40 studies compared WM performance in children or youth with concussion to healthy controls, pre-injury performance, or normative values, of which 15 reported significantly lower WM performance in the concussion sample. Visual/spatial WM was more consistently impacted than verbal WM. Cognitive demanding dual-task conditions were also reliably impacted.Conclusion: Literature indicated that WM is vulnerable to negative outcomes following pediatric concussion, yet the nature of outcomes is variable. Clinicians and researchers should implement comprehensive and theoretically motivated WM assessments to better understand the WM components impacted by injury.

Response patterns to vowel formant perturbations in children.

Auditory feedback is an important component of speech motor control, but its precise role in developing speech is less understood. The role of auditory feedback in development was probed by perturbing the speech of children 4-9 years old. The vowel sound /ɛ/ was shifted to /æ/ in real time and presented to participants as their own auditory feedback. Analyses of the resultant formant magnitude changes in the participants' speech indicated that children compensated and adapted by adjusting their formants to oppose the perturbation. Older and younger children responded to perturbation differently in F1 and F2. The compensatory change in F1 was greater for younger children, whereas the increase in F2 was greater for older children. Adaptation aftereffects were observed in both groups. Exploratory directional analyses in the two-dimensional formant space indicated that older children responded more directly and less variably to the perturbation than younger children, shifting their vowels back toward the vowel sound /ɛ/ to oppose the perturbation. Findings support the hypothesis that auditory feedback integration continues to develop between the ages of 4 and 9 years old such that the differences in the adaptive and compensatory responses arise between younger and older children despite receiving the same auditory feedback perturbation.

Changes in Oxyhemoglobin Concentration in the Prefrontal Cortex during Cognitive-Motor Dual Tasks in People with Chronic Obstructive Pulmonary Disease.

Cognitive and motor impairment are well documented in chronic obstructive pulmonary disease (COPD) patients, but their relationship has not been studied. This study evaluated and compared cognitive and motor performance during dual tasks and related dorsolateral prefrontal cortex (PFC) changes in oxygenated hemoglobin (ΔO2Hb), a proxy measure of neural activity, in patients with COPD and age-matched healthy individuals. Participants performed three single tasks: (1) backwards spelling cognitive task; (2) 30 m preferred paced walk; (3) 30 m fast walk, and two dual tasks: (4) preferred paced walk + backwards spelling; (5) fast paced walk + backwards spelling. The ΔO2Hb from left and right dorsolateral PFC were measured using functional near-infrared spectroscopy. Gait velocity was measured using a Zeno walkway. Compared to healthy adults (n = 20), patients with COPD (n = 15) had higher ΔO2Hb during single preferred (-0.344 ± 0.185 vs. 0.325 ± 0.208 µM; p = 0.011) and fast paced walk (-0.249 ± 0.120 vs. 0.486 ± 0.182 µM; p = 0.001) in right PFC. Among healthy adults, ΔO2Hb were higher bilaterally during preferred paced walking dual versus single task (right: 0.096 ± 0.159 vs. -0.344 ± 0.185 µM, p = 0.013; left: 0.114 ± 0.150 vs. -0.257 ± 0.175 µM, p = 0.049) and in right PFC during fast walking dual versus single task (0.102 ± 0.228 vs. -0.249 ± 0.120, p = 0.021). Patients with COPD did not increase O2Hb during dual versus single tasks. Patients with COPD exhibited slower velocity than older adults during all walking tasks. The lack of further increase in O2Hb from single to dual tasks in patients with COPD, may indicate reduced cognitive-motor capacity and contribute to poorer motor performance limiting safe ambulation. Dual tasking rehabilitation may improve neural efficiency to offset these risks.

Whistling shares a common tongue with speech: bioacoustics from real-time MRI of the human vocal tract.

Most human communication is carried by modulations of the voice. However, a wide range of cultures has developed alternative forms of communication that make use of a whistled sound source. For example, whistling is used as a highly salient signal for capturing attention, and can have iconic cultural meanings such as the catcall, enact a formal code as in boatswain's calls or stand as a proxy for speech in whistled languages. We used real-time magnetic resonance imaging to examine the muscular control of whistling to describe a strong association between the shape of the tongue and the whistled frequency. This bioacoustic profile parallels the use of the tongue in vowel production. This is consistent with the role of whistled languages as proxies for spoken languages, in which one of the acoustical features of speech sounds is substituted with a frequency-modulated whistle. Furthermore, previous evidence that non-human apes may be capable of learning to whistle from humans suggests that these animals may have similar sensorimotor abilities to those that are used to support speech in humans.

Cognitive Communication Impairments in Children With Traumatic Brain Injury: A Scoping Review.

OBJECTIVE: This scoping review synthesizes the scholarly literature on cognitive communication impairments in traumatic brain injury (TBI) sustained during childhood to identify gaps in research, and make recommendations that will further the field of cognitive communication in pediatric TBI. METHODS: MEDLINE, PsycINFO, CINAHL, and EMBASE were searched to identify peer-reviewed studies that examined cognitive communication impairments in children who sustained a TBI between 3 months to 18 years of age. RESULTS: Twenty-eight studies met inclusion criteria with 3 main categories identified in relation to cognitive communication: (1) impairments according to TBI severity, (2) impairments according to age at injury, and (3) trends in recovery according to TBI severity. CONCLUSIONS: The results of this scoping review suggest that (1) TBI severity is not the sole predictor of performance; other factors contribute to cognitive communication outcome and recovery; (2) developing skills at time of injury are most susceptible to impairment; and (3) standard, norm-referenced language assessments are not sensitive in detecting language impairments that are secondary to cognitive impairments found in TBI. Directions for future research and suggestions for clinical practice are proposed.

The neural correlates of speech motor sequence learning.

Speech is perhaps the most sophisticated example of a species-wide movement capability in the animal kingdom, requiring split-second sequencing of approximately 100 muscles in the respiratory, laryngeal, and oral movement systems. Despite the unique role speech plays in human interaction and the debilitating impact of its disruption, little is known about the neural mechanisms underlying speech motor learning. Here, we studied the behavioral and neural correlates of learning new speech motor sequences. Participants repeatedly produced novel, meaningless syllables comprising illegal consonant clusters (e.g., GVAZF) over 2 days of practice. Following practice, participants produced the sequences with fewer errors and shorter durations, indicative of motor learning. Using fMRI, we compared brain activity during production of the learned illegal sequences and novel illegal sequences. Greater activity was noted during production of novel sequences in brain regions linked to non-speech motor sequence learning, including the BG and pre-SMA. Activity during novel sequence production was also greater in brain regions associated with learning and maintaining speech motor programs, including lateral premotor cortex, frontal operculum, and posterior superior temporal cortex. Measures of learning success correlated positively with activity in left frontal operculum and white matter integrity under left posterior superior temporal sulcus. These findings indicate speech motor sequence learning relies not only on brain areas involved generally in motor sequencing learning but also those associated with feedback-based speech motor learning. Furthermore, learning success is modulated by the integrity of structural connectivity between these motor and sensory brain regions.

Motor Evoked Potential Amplitude in Motor Behavior-based Transcranial Direct Current Stimulation Studies: A Systematic Review.

Motor evoked potential amplitude (MEPamp) is frequently measured in transcranial direct current stimulation (tDCS) studies that target the primary motor cortex (M1), and a subset of these studies involve motor behavior. This systematic review explored the role of MEPamp as an indicator of neural change in M1-targeted tDCS studies involving motor behavior (i.e., motor practice and/or evaluation of motor performance) in healthy individuals, and examined the association between changes in motor performance and MEPamp. We executed our search strategy across four bibliographic databases. Twenty-two manuscripts met eligibility criteria. While anodal tDCS combined with motor practice frequently increased MEPamp, MEPamp outcomes did not necessarily align with changes in motor performance. Thus, MEPamp may not be the most appropriate indicator of neural change in tDCS studies that aim to improve motor performance.

Pediatric Responses to Fundamental and Formant Frequency Altered Auditory Feedback: A Scoping Review.

Purpose: The ability to hear ourselves speak has been shown to play an important role in the development and maintenance of fluent and coherent speech. Despite this, little is known about the developing speech motor control system throughout childhood, in particular if and how vocal and articulatory control may differ throughout development. A scoping review was undertaken to identify and describe the full range of studies investigating responses to frequency altered auditory feedback in pediatric populations and their contributions to our understanding of the development of auditory feedback control and sensorimotor learning in childhood and adolescence. Method: Relevant studies were identified through a comprehensive search strategy of six academic databases for studies that included (a) real-time perturbation of frequency in auditory input, (b) an analysis of immediate effects on speech, and (c) participants aged 18 years or younger. Results: Twenty-three articles met inclusion criteria. Across studies, there was a wide variety of designs, outcomes and measures used. Manipulations included fundamental frequency (9 studies), formant frequency (12), frequency centroid of fricatives (1), and both fundamental and formant frequencies (1). Study designs included contrasts across childhood, between children and adults, and between typical, pediatric clinical and adult populations. Measures primarily explored acoustic properties of speech responses (latency, magnitude, and variability). Some studies additionally examined the association of these acoustic responses with clinical measures (e.g., stuttering severity and reading ability), and neural measures using electrophysiology and magnetic resonance imaging. Conclusion: Findings indicated that children above 4 years generally compensated in the opposite direction of the manipulation, however, in several cases not as effectively as adults. Overall, results varied greatly due to the broad range of manipulations and designs used, making generalization challenging. Differences found between age groups in the features of the compensatory vocal responses, latency of responses, vocal variability and perceptual abilities, suggest that maturational changes may be occurring in the speech motor control system, affecting the extent to which auditory feedback is used to modify internal sensorimotor representations. Varied findings suggest vocal control develops prior to articulatory control. Future studies with multiple outcome measures, manipulations, and more expansive age ranges are needed to elucidate findings.